1. Field of the Invention
The present invention relates to improvements in ball-lock-type quick-acting connectors which may be used in a variety of applications including automotive fuel injection systems, hydraulic systems and pneumatic systems to detachably connect fluid lines or pipes by a single action.
2. Description of the Prior Art
Ball-lock-type quick-acting connectors or pipe couplings are well-known and have been used in various fields of industries.
As shown in FIGS. 1 and 2 of the accompanying drawings, the conventional ball-lock type connector typically includes a socket member 1 and a plug member 2 which are adapted to be detachably coupled with each other in a telescoping fashion, the members being suitably attached by threaded couplings and the like to the ends of respective fluid lines to be connected.
The socket 1 is provided with a plurality of tapered through-holes or pockets 3 that are circumferentially equally spaced apart from one another. Each pocket 3 receives a locking ball 4 made of steel which is adapted to partly protrude radially inwardly of the pocket to thereby engage within an annular groove 5 formed on the outer circumference of the plug 2. The connector further includes a spring-biased control sleeve or slider 6 which is slidably fitted over the socket 1 to control the radial position of the locking balls.
To connect the socket and plug members, the control sleeve 6 is first retracted against the spring bias as shown in FIG. 2 and the plug is then inserted into the socket until the groove 5 is brought into registration with the pockets 3. Then the sleeve is returned to the locking position shown in FIG. 1 whereby the locking balls 4 are cammed into the groove 5 to retain the socket and plug together. An O-ring 7 mounted within an annular seal ring groove 8 formed on the inner periphery of the socket establishes a fluid-tight seal between the socket and plug members. The return coil spring serves to keep the control sleeve in its locking position.
To disconnect the socket and plug, the control sleeve is moved to the unlocking position shown in FIG. 2 to release the locking balls. As the plug is then pulled away from the socket, the locking balls 4 are cammed out of the annular groove 5 as shown in FIG. 2 to thereby permit the plug member to be pulled out of the socket member.
In applications wherein the connector is subjected to a high fluid pressure, a backup ring 9 is normally used and is arranged within the seal ring groove 8 at the downstream side of the O-ring 7 to back-up the O-ring.
The problem associated with the conventional quick-acting connectors is that they are costly to manufacture because the major parts thereof, such as the socket, plug and control sleeve, must be made by using machine tools such as lathe, drilling and milling machines.
Moreover, the presence of the seal ring groove on the inner surface that defines the bore of the socket member involves a number of problems. First, machining of the seal ring groove is difficult to perform at a high precision because during machining a cutting tool must be inserted and positioned inside the narrow bore of the socket.
More importantly, the O-ring tends to be twisted and distorted as it is inserted into the socket since the outer diameter of the O-ring is generally larger than the inner diameter of the socket bore and, therefore, the O-ring must be radially compressed or deformed to a substantial degree prior to and during insertion into the bore of the socket. If the O-ring as finally installed within the seal ring groove is in a twisted or distorted state, there is a risk of fluid leakage. In addition, the plug member would bite into the O-ring to thereby damage the O-ring each time the plug is inserted into the socket.
When the O-ring once fitted in the seal ring groove is to be dismounted therefrom for inspection or for any other reasons, a sharp tool such as a hook must be used to scoop the O-ring out of the groove. This tends to damage the O-rings and prevents their re-use.
Furthermore, the overall wall thickness of the socket member must be selected to be large enough to provide a sufficient mechanical strength even after the material which forms the socket wall is partly removed by cutting or milling to form the seal ring groove. This prevents reduction in weight of the connectors and results in an increase in the production costs.